Method and apparatus for operating wireless communication system having separated mobility management and session management

ABSTRACT

The present invention defines signaling required for separating a network entity (NE) responsible for mobility management (MM) and session management (SM), which are main function of a control plane (CP) in a next generation (NextGen) mobile communication system, and presents a basic procedure for providing mobile communication services including the signaling. Therefore, complexity of core equipment responsible for the CP is reduced in order to implement a network slice function and provide various levels of mobility, and an effect of minimizing a signaling load therebetween can be obtain. In addition, it is possible to efficiently manage the resources of a base station (radio access network (RAN)) and a user plane network entity (UP NF).

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation application of prior application Ser.No. 16/327,139, filed on Feb. 21, 2019, which will be issued as U.S.Pat. No. 11,224,079 on Jan. 11, 2022, which is a U.S. National Stageapplication under 35 U.S.C. § 371 of an International application numberPCT/KR2017/009142, filed on Aug. 22, 2017, which was based on andclaimed priority under 35 U.S.C. § 119(e) of a U.S. Provisionalapplication Ser. No. 62/377,889, filed on Aug. 22, 2016, in the U.S.Patent and Trademark Office, the disclosure of which is incorporated byreference herein in its entirety.

TECHNICAL FIELD

The present invention relates to a 5G cellular communication system and,particularly, to a method for supporting a structure of separatingmobility management and session management on a control plane of a coreequipment.

BACKGROUND ART

In order to evolve a 5G system from the existing 4G LTE system, the3GPP, which is in charge of the cellular mobile communication standard,has named a new core network structure as NextGen Core (NG Core) and isproceeding with standardization.

Compared to Evolved Packet Core (EPC) which is a network core for theexisting 4G, the NG Core aims to support the following differentiatedfunctions. First, a network slice function is introduced. As therequirement of the 5G, the NG Core should support various terminal typesand services. For example, it is required to support terminal types andservices such as enhanced Mobile Broadband (eMBB), Ultra Reliable LowLatency Communications (URLLC), and massive Machine Type Communications(mMTC).

Each terminal/service has different requirements for the core network.For example, an eMBB service may require a high data rate, and a URLLCservice may require high stability and low latency. A technique tosatisfy these various service requirements is a network slice scheme.

The network slice is a way of creating multiple logical networks throughvirtualization of a single physical network. First, each network sliceinstance (NSI) may have different characteristics. This is realized wheneach NSI has a network function (NF) corresponding to the characteristicthereof. For example, it is possible to efficiently support various 5Gservices by allocating a suitable NSI for a required servicecharacteristic to each terminal.

Second, a mobility management function and a session management functionmay be separated. In the existing 4G LTE, all terminals can receiveservices from the network through a signaling exchange with single coreequipment called a Mobility Management Entity (MME) responsible forregistration, authentication, mobility management, and sessionmanagement functions. However, because the number of terminals isexplosively increased in the 5G and also the mobility andtraffic/session characteristics to be supported according to theterminal type are divided, supporting all functions at single equipmentsuch as the MME causes lower efficiency. Therefore, in order to improvethe efficiency in terms of function/implementation complexity andsignaling load of the core equipment responsible for the control plane,an approach of separating the mobility management function and thesession management function is being discussed intensively.

DISCLOSURE OF INVENTION Technical Problem

It is an object of the present invention to define essential signalingbetween network entities in a structure where a mobility managementfunction and a session management function are separated from each otherin a core of a cellular mobile communication system. In particular, whena terminal sets up a plurality of Protocol Data Unit (PDU) sessions, aprocedure between a terminal and a network entity is defined toselectively operate respective data transmission paths.

Solution to Problem

According to an embodiment of the present invention, a method of aterminal may comprise selecting a Protocol Data Unit (PDU) session fortransmission of data from among at least one inactivated PDU session;transmitting a service request message including identificationinformation of the selected session to a mobility management functionelement for managing mobility of the terminal; and transmitting the datathrough the selected PDU session activated based on the service requestmessage.

In addition, according to an embodiment of the present invention, amethod of a mobility management function element may comprise receiving,from a terminal, a service request message including identificationinformation of a specific Protocol Data Unit (PDU) session; andtransmitting, to a specific session management function elementcorresponding to the identification information of the specific PDU, apath setup trigger message for data transmission to a user plane networkfunction element of the terminal.

In addition, according to an embodiment of the present invention, amethod of a session management function element may comprise receiving,from a mobility management function element for managing mobility ofterminal, a path setup trigger message for data transmission to a userplane network function element of the terminal; and transmittingsignaling related to the path setup to the mobility management functionelement, wherein the path setup trigger message is received when themobility management function element determines that a specific ProtocolData Unit (PDU) session for the data transmission is managed by thesession management function element, and wherein the specific PDUsession is selected by the terminal from among at least one inactivatedPDU session.

According to an embodiment of the present invention, a terminal maycomprise a transceiver and a controller configured to select a ProtocolData Unit (PDU) session for transmission of data from among at least oneinactivated PDU session, to control the transceiver to transmit aservice request message including identification information of theselected session to a mobility management function element for managingmobility of the terminal, and to control the transceiver to transmit thedata through the selected PDU session activated based on the servicerequest message.

In addition, according to an embodiment of the present invention, amobility management function element may comprise a transceiverconfigured to receive, from a terminal, a service request messageincluding identification information of a specific Protocol Data Unit(PDU) session; and a controller configured to control the transceiver totransmit, to a specific session management function elementcorresponding to the identification information of the specific PDU, apath setup trigger message for data transmission to a user plane networkfunction element of the terminal.

In addition, according to an embodiment of the present invention, asession management function element may comprise a transceiverconfigured to receive, from a mobility management function element formanaging mobility of terminal, a path setup trigger message for datatransmission to a user plane network function element of the terminal;and a controller configured to control the transceiver to transmitsignaling related to the path setup to the mobility management functionelement, wherein the path setup trigger message is received when themobility management function element determines that a specific ProtocolData Unit (PDU) session for the data transmission is managed by thesession management function element, and wherein the specific PDUsession is selected by the terminal from among at least one inactivatedPDU session.

Advantageous Effects of Invention

As described above, the present invention can reduce the implementationcomplexity of the core equipment responsible for the control plane (CP)to implement a network slice function and provide various levels ofmobility, thus minimizing a signaling load therebetween. In addition,even if the terminal frequently performs handover, it is possible toreduce the signaling load between the base station (radio access network(RAN)) and the NF of the core network and also efficiently manage theresources of the user plane network entity (UP NF).

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating network architecture of a cellularmobile communication system according to an embodiment of the presentinvention.

FIGS. 2A and 2B are diagrams illustrating a process of setting up asession related to a terminal according to an embodiment of the presentinvention.

FIGS. 3A and 3B are diagrams illustrating a process of setting up asession related to a terminal according to another embodiment of thepresent invention.

FIG. 4 is a diagram illustrating a PDU session release procedureaccording to an embodiment of the present invention.

FIG. 5 is a diagram illustrating a signaling and user plane transmissionpath setup procedure of a terminal in case of uplink traffic in an idlestate according to an embodiment of the present invention.

FIG. 6 is a diagram illustrating a process of an idle-state terminal toreceive downlink traffic from a data network according to an embodimentof the present invention.

FIG. 7 is a diagram illustrating a handover procedure in case wherethere is an X2 interface between a source base station and a target basestation in a MM/SM separated core structure according to an embodimentof the present invention.

FIG. 8 is a diagram illustrating a handover procedure in case wherethere is no X2 interface between a source base station and a target basestation in a MM/SM separated core structure according to an embodimentof the present invention.

FIG. 9 is a diagram illustrating a TAU procedure for updating a locationof a terminal in a network according to an embodiment of the presentinvention.

FIG. 10 is a diagram illustrating a base station operation when there isno data transmission for a given time in a state where a PDU session isset up in a terminal according to an embodiment of the presentinvention.

FIG. 11 is a diagram illustrating a procedure for releasing a signalingconnection between a terminal and an MM according to an embodiment ofthe present invention.

FIG. 12 is a diagram illustrating necessary information for each entityto perform a process according to an embodiment of the presentinvention.

FIG. 13 is a block diagram illustrating a configuration of a terminalaccording to an embodiment of the present invention.

FIG. 14 is a block diagram illustrating a configuration of a mobilitymanagement function element according to an embodiment of the presentinvention.

FIG. 15 is a block diagram illustrating a configuration of a sessionmanagement function element according to an embodiment of the presentinvention.

MODE FOR THE INVENTION

Now, embodiments of the present invention will be described in detailwith reference to the accompanying drawings. In the followingdescription of the present invention, detailed description of knownfunctions and configurations incorporated herein will be omitted when itmay make the subject matter of the present invention rather unclear. Thefollowing terms are defined in consideration of the functions of thepresent invention, and may be changed according to the intention of theuser, the operator, or the like. Therefore, the definition should bebased on the contents throughout this specification.

In this disclosure, a base station (BS), which is an entity ofperforming resource allocation for a terminal, may be at least one of anevolved Node B (eNode B), a Node B, a radio access network, a radioaccess unit, a base station controller, or a node on the network. Aterminal may include a user equipment (UE), a mobile station (MS), acellular phone, a smart phone, a computer, or a multimedia systemcapable of performing communication function.

In this disclosure, a downlink (DL) is a wireless transmission path of asignal transmitted from a base station to a terminal, and an uplink (UL)is a wireless transmission path of a signal transmitted from a terminalto a base station. In the following, embodiments of the presentinvention will be described using the LTE or LTE-A system as an example,but such embodiments may be also applied to any other communicationsystem having a similar technical background or channel form. It isapparent to a person skilled in the art that embodiments of theinvention may be applied to other communication systems through somemodifications within the scope of the invention.

Briefly, the present invention defines a new signaling between amobility management apparatus and a session management apparatus in acore of a cellular mobile communication system, thereby proposing aservice provision procedure that satisfies various requirements of anetwork operator and a terminal. Necessaries are as follows.

Hereinafter, for convenience, a terminal and a UE are usedinterchangeably, and also a base station and an RAN are usedinterchangeably. In addition, terms used in describing embodiments ofthe invention may be replaced by other terms. For example, a user planenetwork function (UP NF) may be replaced with a user plane function(UPF). A mobility management (MM) may be replaced with a mobilitymanagement network function (MM NF), a mobility management function(MMF), or an access and mobility function (AMF). A session management(SM) may be replaced with a session management network function (SM NF)or session management function (SMF).

FIG. 1 is a diagram illustrating network architecture of a cellularmobile communication system according to an embodiment of the presentinvention.

Referring to FIG. 1, a network of a cellular mobile communication systemaccording to an embodiment of the present invention may include a UE101, an RAN 102, a user plane network function (UP NF) 103, a datanetwork (DN) 104, a subscriber data management (SDM) 105, a mobilitymanagement (MM), a session management (SM) 108, and a policy control(PC) 106. In addition, the MM according to an embodiment of the presentinvention may include a control plane (CP) signaling routing function107 a.

The UP NF 103 according to an embodiment of the present invention isconnected to the RAN 102 inside the network through an NG3 (or N3)interface and connected to the DN 104 through an NG6 (or N6) interface.The UP NF 103 includes the role of a gateway (GW) directly connected tonetwork equipment outside the network, and enables data communicationbetween the UE 101 and the DN 104 (e.g., Internet) while being locatedon a data transmission path with the RAN 102 inside the network.

The SDM 105, which is a server for managing UE subscription information,may perform registration and authentication, and also obtain informationwhen determining a service level to be provided to the UE in thenetwork. The PC 106, which is a server that manages Quality of Service(QoS) rules, is core equipment having to perform an interaction when theSM 108 establishes a transmission path to the UP NF 103 and the RAN 102.

Principal core equipment in the present invention is the MM 107 formanaging the mobility of the UE and the SM 108 for managing a sessionrelated to the UE. The MM 107 according to an embodiment of the presentinvention may be connected to the UE 101 through an NG1 (or N1)interface and connected to the RAN 102 via an NG2 (or N2) interface.Also, the SM 108 according to an embodiment of the present invention maybe connected to the UP NF 103 via an NG4 (or N4) interface.

The MM 107 responsible for mobility management of the UE has the CPsignaling routing function 107 a, which performs routing to the MM 107or the SM 108 depending on whether the destination of signaling sent bythe UE 101 or the RAN 102 is the MM 107 or the SM 108. This routingfunction does not need to interpret what content the signaling messagehas, so that the MM 107 has an advantage of reduced implementationcomplexity because of no need of managing the context associated with asession of the UE.

The present invention is described on the assumption that when the UE isallocated a single network slice, it is associated with a plurality ofSMs. However, even if the SM is allocated per network slice, thefollowing procedures are all applicable. The network entity name orinterface name shown in FIG. 1 may be changed, but its role and functionmay be maintained. For example, in case of the interface name, NG # mayalso be represented in the form of N #.

Another important point of the present invention is to efficientlyoperate a plurality of PDU sessions when the UE sets up (establishes)such PDU sessions. A state of the PDU session may be defined as follows.A state where a user plane (UP) connection of the PDU session is set upand thus allows immediate data transmission is defined as an activatedstate. On the other hand, a state of requiring a UP connection setupprocedure to send data because of no existence of UP connection of thePDU session is defined as a deactivated state.

When the PDU session is set up at the request of the UE or network, asession management function (SMF), which is a core network entity formanaging a session, selects a user plane function (UPF) performing therole of a gateway (GW) for connecting the PDU session with an externaldata network, and sets up a NG3 (or N3) tunnel, which is a datatransmission path of the PDU session, between the UPF and the RANcurrently accessed by the UE.

Also, a data radio bearer (DRB) for supporting the PDU session is set upbetween the UE and the RAN. At this time, in order to make the DRBsatisfy the QoS requirement of the PDU session, the RAN may set up theDRB that satisfies a plurality of different QoS requirements. The userplane (UP) connection of the PDU session may be composed of the N3tunnel and the DRB.

If the UE frequently performs handover by movement in a state ofactivating the UP connection of the PDU session, signaling that enablesthe N3 tunnel and the DRB constituting the UP connection of the PDUsession to change a data transmission path to go via a target RAN from asource RAN occurs. Specifically, even if traffic of an application usingthe PDU session does not actually occur, the signaling to route the N3tunnel and DRB of the PDU session to the target RAN is required wheneverhandover occurs. This signaling overhead problem may become more seriousas the number of PDU sessions simultaneously set up by the UE increases.In order to solve this problem, a method of selectively activating andoperating the UP connection of the PDU session in which traffic isactually transmitted is proposed.

Details will be described later with reference to FIG. 5 illustrating aUE triggered service request procedure and FIG. 6 illustrating a networktriggered service request procedure.

FIGS. 2A and 2B are diagrams illustrating a process of setting up asession related to a terminal according to an embodiment of the presentinvention.

FIGS. 2A and 2B presume a state where the terminal (UE) has been alreadyregistered in the MM through a complete access (attach) to the networkin the network architecture shown in FIG. 1. Thus, in this embodiment,the MM 207 has already issued an ID (UE ID) of the UE 201 and knows theRAN 202 to which the UE 201 is attached (e.g., knows an ID (RAN ID) ofthe RAN to which the UE is attached). Also, the UE 201 according to anembodiment of the invention may be in a state of knowing an ID (MM ID)of the MM 207 and a data network name (DNN).

Now, a procedure is described in which the UE 201 requests a new PDUsession establishment for data communication. The PDU session refers toan association between the UE and the data network (DN). The PDU sessionis similar to a packet data network (PDN) connection in the 4G LTE, andmay include an Internet Protocol (IP), non-IP, and Ethernet. Inaddition, as an ID of each network entity, an IP address, a system ID,and any other identifier capable of distinguishing each entity in thenetwork may be used.

Referring to FIGS. 2A and 2B, the UE 201 transmits a PDU sessionestablishment request message to the MM 207 (S201). Here, the PDUsession establishment request message may contain a UE ID, a DNN, a PDUtype, a UE capability, and session and service continuity (SSC) modeinformation.

Upon receiving the PDU session establishment request message, the MM 207performs a signaling routing function (S202). If an SM ID is notspecified, the MM 207 forwards or relays, as a result of performing thesignaling routing function, the PDU session establishment requestmessage to a default SM 208 a (S203). Here, the MM 207 and the defaultSM 208 a may be co-located at the same place. Through the forwardingprocess (S203), the UE ID, the DNN, the PDU type, the UE capability, andthe SSC mode information contained in the PDU session establishmentrequest message may be delivered to the default SM 208 a.

If the MM 207 has UE subscription information through the attach processof the UE, the UE ID and the DNN may be transmitted to the default SM208 a through a process of UE subscription request/response (S204)between the MM 207 and the default SM 208 a.

The default SM 208 a selects a suitable SM (S205) by performing asession management (SM) selection, based on the UE subscription, theDNN, the PDU type, the UE capability, and the SSC mode. At this time,the default SM 208 a transmits the selected SM ID and UE ID to the MM207 so that the selected SM ID and UE ID can be registered in the MM 207(S206). Also, the MM 207 performs transmission, to a chosen SM 208 b,for registration of an MM ID and an RAN ID to which the UE 201 belongs(S207). Then, the default SM 207 a delivers the received PDU sessionestablishment request to the chosen SM 208 b through the MM 207 (S208).

After receiving the PDU session establishment request, the chosen SM 208b performs a process of applying an operator policy (S209) with the PC206 and selects the UP NF 203 (S210). Then, the chosen SM 208 b performsa transmission path setup with the selected UP NF 203 and DN 204. Forexample, the chosen SM 208 b may send a session creation request to theselected UP NF 203 and receive a response to the session creationrequest from the UP NF 203 (S211).

Meanwhile, the chosen SM 208 b also performs a transmission path setupwith the RAN 202. For example, the chosen SM 208 b may transmit, to theRAN 202, an initial context setup request that contains the UE ID, theSM ID, a session ID, an RAN tunnel endpoint ID (TEID) for uplink, andthe RAN ID (S212). Then, the RAN 202 establishes a radio bearer with theUE 201 (S213) and may transmit an initial context setup response to thechosen SM 208 b (S214). Here, the initial context setup response maycontain the UE ID, the SM ID, the session ID, the RAN TEID [DL], and theRAN ID.

Upon reception of the initial context setup response, the chosen SM 208b performs a session modification request/response process with the UPNF 203 (S215). As a result, the transmission path setup is completedbetween the DN 204, the UP NF 203, the RAN 202, and the UE 201. When thetransmission path setup is completed, the chosen SM 208 b transmits, tothe MM 207, a PDU session establishment response signaling including theUE ID, the DNN, the SM ID, the session ID, and a UE IP (S216), and theMM 207 may transmit a PDU session establishment response including theSM ID, the session ID, and the UE IP to the UE 201 (S217). Then, the UE201 can transmit/receive uplink/downlink IP traffic (data communication)with the DN 204 through the set transmission path (S218).

FIGS. 3A and 3B are diagrams illustrating a process of setting up asession related to a terminal according to another embodiment of thepresent invention.

Referring to FIGS. 3A and 3B, the terminal (UE) 301 transmits a PDUsession establishment request to the MM 307 (S301). Like the above caseas shown in FIGS. 2A and 2B, it is assumed that the UE has been alreadyregistered in the MM through a complete access (attach) to the networkin the network architecture according to an embodiment of the invention.That is, the UE 301 knows the MM ID and the DNN, and the MM 307 may knowthe UE ID and the RAN ID. Also, as in FIGS. 2A and 2B, the PDU sessionestablishment request may contain the UE ID, the DNN, the PDU type, theUE capability, and the SSC mode.

The MM 307 performs a signaling routing function (S302). If the SM ID isnot specified, the MM 307 may relay the PDU session establishmentrequest to the default SM 308 a. As described above with reference toFIGS. 2A and 2B, the MM 307 and the default SM 308 a may be co-located.Therefore, the UE ID, the DNN, the PDU type, the UE capability, and theSSC mode information may be included in the PDU session establishmentrequest message and transmitted to the default SM 308 a.

Assuming that the MM 307 has UE subscription information through theattach process of the UE, the UE ID and the DNN may be transmitted tothe default SM 308 a through a process of UE subscriptionrequest/response (S304) between the MM 307 and the default SM 308 a.Then, the default SM 308 a selects a suitable SM (S305) by performing asession management (SM) selection, based on the UE subscription, theDNN, the PDU type, the UE capability, and the SSC mode.

Unlike FIGS. 2A and 2B, in this embodiment, the chosen SM 308 b maydirectly register with the MM. Specifically, the default SM 308 a maysend a PDU session establishment request to the chosen SM 308 b. At thistime, the PDU session establishment request may contain the UE ID, theDNN, the PDU type, the UE capability, the SSC mode, and the MM ID. As anexample, the MM ID may be transferred from the default SM 308 a to thechosen SM 308 b via other signaling.

Thereafter, the chosen SM 308 b performs the SM ID registration with theMM 307 through a signaling including the UE ID and the SM ID (S307). Inresponse, the MM 307 may send a signaling including the UE ID and theRAN ID to the chosen SM 308 b to perform the RAN ID registration processwith the chosen SM 308 b (S308).

In addition, the chosen SM 308 b performs a process of applying anoperator policy (S309) with the PC 306 and selects the UP NF (S310).Then, the chosen SM 308 b performs a transmission path setup with theselected UP NF 303 and DN 304. For example, the chosen SM 308 b may senda session creation request to the selected UP NF 303 and receive aresponse to the session creation request from the UP NF 303 (S311).

Meanwhile, the chosen SM 308 b also performs a transmission path setupwith the RAN 302. For example, the chosen SM 308 b may transmit, to theRAN 302, an initial context setup request that contains the UE ID, theSM ID, the session ID, the RAN tunnel endpoint ID (TEID) for uplink, andthe RAN ID (S312). Then, the RAN 302 establishes a radio bearer with theUE 301 (S313) and may transmit an initial context setup response to thechosen SM 308 b (S314). Here, the initial context setup response maycontain the UE ID, the SM ID, the session ID, the RAN TEID [DL], and theRAN ID.

Upon reception of the initial context setup response, the chosen SM 308b performs a session modification request/response process with the UPNF 303 (S315). As a result, the transmission path setup is completedbetween the DN 304, the UP NF 303, the RAN 302, and the UE 301. When thetransmission path setup is completed, the chosen SM 308 b transmits, tothe MM 307, a PDU session establishment response signaling including theUE ID, the DNN, the SM ID, the session ID, and the UE IP (S316), and theMM 307 may transmit a PDU session establishment response including theSM ID, the session ID, and the UE IP to the UE 301 (S317). Then, the UE301 can transmit/receive uplink/downlink IP traffic (data communication)with the DN 304 through the set transmission path (S318).

Now, a PDU session release procedure according to an embodiment of theinvention will be described with reference to FIG. 4. This procedure maybe performed based on a request of the UE or SM. The procedure based onthe request of the UE is performed sequentially from S401, and theprocedure based on the request of the SM is performed from S403.

If there is at step S403 any session other than a session to bereleased, step S404 is skipped. On the other hand, if the session to bereleased is the last session for the UE, the MM 407 is requested torelease the SM ID through step S404. The SM 408 that receives a requestfor a session release performs a process of releasing the transmissionpath previously set with the UP NF 403 and the RAN 402. When this iscompleted, the SM 408 finally transmits a signaling of releasecompletion to the UE 401.

Specifically, referring to FIG. 4, the UE 401 transmits a PDU sessionrelease request to the MM 407 (S401). Here, the PDU session releaserequest may contain a UE ID, an SM ID, and a session ID. The MM 407 mayforward the PDU session release request received from the UE 401 to theSM 408 (S402).

The SM 408 may check the existing PDU session (S403) and performsignaling for the SM ID registration release to the MM 407 (S404). Here,the SM ID registration release may include the UE ID and the SM ID. Inaddition, the SM 408 may send a session release request including the UEID, the SM ID and the session ID to the UP NF 403 (S405) and receive thesession release response including the UE ID from the UP NF 403 (S406).Upon reception of the session release response, the SM 408 may send asession deactivation request to the MM 407 (S407). Here, the sessiondeactivation request may include the UE ID, the SM ID, and the sessionID. When the session deactivation request including the UE ID, the SM IDand the session ID is delivered from the MM 407 to the RAN 402 (S408), aradio bearer release procedure may be performed between the UE 401 andthe RAN 402 (S409).

Thereafter, the RAN 402 transmits a session deactivation responseincluding the UE ID, the SM ID, and the session ID to the MM 407 (S410),and the MM 407 may forward the session deactivation response includingthe UE ID, the SM ID and the session ID to the SM 408 (S411). Inaddition, when a PDU session release response including the UE ID, theSM ID and the session ID is received from the SM 408, the MM 407transmits a signaling of the PDU session release response including theSM ID and the session ID to the UE 401 (S413).

Described with reference to FIG. 5 is a process for a control planesignaling connection with a network and a user plane transmission pathsetup when uplink (UL) traffic is generated in a terminal (UE) in anidle state.

The idle state may be defined depending on whether a signalingconnection state between the UE and the cellular network is set up. Forexample, the UE may distinguish the idle state from a connected state,based on a radio resource control (RRC) connection state with a cellularbase station. For this procedure, the UE that receives a paging messagefrom the network due to occurrence of downlink (DL) traffic responds tothe paging message.

FIG. 5 assumes that an NG1 signaling connection between the UE 501 andthe MM 507 and an NG2 signaling connection between the RAN 502 and theMM 507 have been set up. First, the UE 501 transmits, to the MM 507, asignaling of a service request that indicates which SM the trafficgenerated by the application layer is to be forwarded to (S501). At thistime, the UE 501 may transmit, to the SM 508 managing a correspondingPDU session, a service request including information for identifying thePDU session to activate a user plane (UP) connection of the PDU session.

For example, the PDU session identification information may be a PDUsession ID, or a corresponding activation flag may be defined and usedbetween the UE and the network. For example, FIG. 5 shows a case wherethe UE 501 inserts a UE ID and an SM ID, as information for identifyingthe PDU session, in the service request.

In addition, in order to handle a case where the SM 508 sets up aplurality of PDU sessions for the UE 501, the identification informationof the PDU session may be unique within one SM. After the MM 507receives the service request from the UE 501, an authentication andsecurity procedure may be performed between the UE 501 and the SDM 505(S502).

Then, based on the service request, the MM 507 transmits a UP path setuptrigger message for setup of a user plane transmission path to thecorresponding SM 508 (S503). Specifically, the MM 507 that receives theservice request message from the UE 501 may confirm the PDU sessionidentification information included in the service request and transmita signaling for activating the UP connection to the SM 508 managing thesession. Here, the UP path setup trigger message, which is the signalingfor activating the UP connection, may include the UE ID and the RAN ID.

The SM 508 that receives the activation message for the PDU session maytransmit, in order to activate a UP connection of the PDU session, an N2session setup request signaling for the UP connection setup to the RAN502 currently accessed by the UE 501. This signaling may be, forexample, an initial context setup request signaling as shown in FIG. 5,and may contain the UE ID, the PDU session ID for sessionidentification, information related to the tunnel of the UP NF (e.g.,the UP address of the UP NF and the tunnel ID of the UP NF) required foruplink traffic transmission.

The RAN 502 that receives the signaling may allocate resources forsetting up the N3 tunnel with the UP NF 503, and perform, with the UE, aprocedure (radio bearer establishment) of generating a DRB that cansatisfy the QoS of the PDU session (S505). When the step S505 iscompleted, the UE 501 may send uplink (UL) traffic to the UP NF 503 viathe RAN 502.

Thereafter, the RAN 502 may generate an N2 session setup responsesignaling to be delivered to the SM 508, including the RAN tunnelidentification information set for the N3 tunnel setup. The N2 sessionsetup response signaling (shown as an initial context setup responsesignaling) may be transmitted to the MM 507, and then the MM 507 maycheck the PDU session identification information and forward thesignaling to the SM 508 (S506).

In addition, the SM 508 may transmit a session modification requestsignaling to the UP NF 503 (S507), and the UP NF 503 may transmit asession modification response to the SM 508. Then, downlink (DL) trafficmay be transmitted from the UP NF 503 to the UE 501. Specifically, atstep S507, the SM 508 may transmit the RAN tunnel identificationinformation received at step S506 to the UP NF 503, so that the N3tunnel setup can be completed between the RAN 502 of the PDU session andthe UP NF 503. At step S508, the UP NF 503 may transmit an N4 sessionmodification response message for the N4 session modification requestsignaling received at step S507.

Through the procedure of FIG. 5, even in case of having a plurality ofPDU sessions, the UE can selectively activate only the UP connection ofa specific PDU session.

FIG. 6 is a diagram illustrating a process of an idle-state terminal toreceive downlink traffic from a data network (DN) according to anembodiment of the present invention.

Specifically, the UP NF 603 that receives the DN traffic may transmit aDL data notification signaling to notify the arrival of DL data to theSM 608 managing the corresponding PDU session (S601). At this time, forcases where one SM 608 manages a plurality of PDU sessions for the sameUE, the above signaling may contain the ID of the corresponding PDUsession together with the UE ID.

In addition, the DL data notification message may be forwarded from theSM 608 to the MM 607 managing the mobility of the UE 601 (S602).Thereafter, for an NG3 setup trigger, the MM 607 may register the ID ofthe SM 608 that sent the DL data notification (S603). This is because,even if a service request in which an SM ID is not specified is receivedfrom the UE when a UE triggered service request procedure is performed,it is possible to send a UP path setup trigger for setup of the userplane to the SM corresponding to a stored SM ID.

At step S603, the MM 507 may store the PDU session identificationinformation included in the DL data notification message, and transmit aDL data notification response (ack) including the UE ID to the SM 608(S604). Then, the SM 508 may transmit the DL data notification ack tothe UP NF 603 (S605). In addition, the MM 507 transmits paging includingthe UE ID to the RAN 602 (S606), and the RAN 602 transmits the paging tothe UE 601 (S607).

Accordingly, a UE triggered service request procedure is performedbetween the UE 601, the RAN 602, the MM 607, the SM 608, and the UP NF603 (S608). For example, when receiving the service request messagetransmitted from the UE 601, the MM 607 may transmit a signaling foractivating the UP connection to the corresponding SM 608 for the storedPDU session. The subsequent operations for completing the UP connectionsetup may be as described in FIG. 5.

Through FIGS. 5 and 6 as described above, the UE can re-establish onlythe UP path (or connection) of the PDU session requiring traffictransmission, so that it is possible to effectively utilize the networkresources for the UP connection unlike the service quest of the existingLTE.

FIG. 7 is a diagram illustrating a handover procedure in case wherethere is an X2 interface between a source base station (source RAN,e.g., RAN1) and a target base station (target RAN, e.g., RAN2) in aMM/SM separated core structure according to an embodiment of the presentinvention.

First, uplink and downlink traffic (UL/DL traffic) may be transmittedand received between the UE 701, the RAN1 702 a, the UP NF1 703 a, andthe DN 704. At this time, a procedure of executing a handover betweenthe UE 701, the RAN1 702 a, and the RAN2 702 b, that is, from the RAN1702 a to the RAN2 702 b, may be performed (S700). In this handoverexecution step, it is assumed that a RAN ID update of the MM 707 is alsoperformed.

When the handover is executed, a path switch request may be transmittedfrom the RAN2 702 b to the SM 708. At this time, the path switch requestmay include a UE ID, a SM ID, a session ID, a TEID [DL] for the RAN2,and a RAN ID. Here, the path switch request is sent only to the SM wherethe UP path is set up.

The SM 708 may determine whether to perform a UP NF relocation triggeredby the path switch request (S702). In this embodiment, the case of norelocation of the UP NF will be described. In case where the relocationof the UP NF is required, the SM 708 can proceed with additionalprocedures.

The SM 708 transmits a session modification request including the UE ID,the SM ID, the session ID, the RAN TEID, and the RAN ID to the UP NF1703 a (S703), and receives a session modification response including theUE ID, the SM ID, and the session ID from the UP NF1 703 a (S704). Atthis time, the UP NF1 703 a may send an “end marker” packet to the RAN1702 a. Then, the SM 708 may send a path switch response including the UEID, the SM ID, and the session ID to the RAN2 702 b (S705).

When the above process is completed, the UE 701 may perform transmissionand reception of UL/DL traffic with the RAN2 702 b, the UP NF1 703 a,and the DN 704. In addition, the RAN2 702 b may transmit a releaseresource signaling including the UE ID to the RAN1 702 a (S706), and atracking area update procedure may be performed between the UE 701, theRAN1 702 a, the RAN2 702 b, and the MM 707 (S707).

FIG. 8 shows a handover procedure from the RAN1 to the RAN2 by using theMM in case where there is no X2 interface. As in FIG. 7, when the UEattaches to the RAN2, the RAN2 sends a path switch request only to theSM in which the transmission path is set between the RAN and the UP NF.

Referring to FIG. 8, UL/DL traffic may be transmitted/received betweenthe UE 801, the RAN1 802 a, the UP NF1 803 a, and the DN 804. At thistime, the RAN1 802 a may transmit a signaling to the MM 807 to inform ahandover required (S801). Based on this signaling, the MM 807 mayperform a handover request/ack procedure with the RAN2 802 b (S802). Atthis step S802, the RAN ID may be updated in the MM 807.

Thereafter, an indirect data forwarding tunnel setup procedure may beperformed between the MM 807, the SM 808, and the UP NF1 803 a (S803).In addition, a signaling of a handover command may be transmitted fromthe MM 807 to the UE 801 (S804). Accordingly, a handover from the RAN1802 a to the RAN2 802 b is performed between the UE 801, the RAN1 802 a,the RAN2 802 b, and the MM 807 (S805).

The UE 801 transmits a handover confirm signaling to the RAN2 802 b(S806). The RAN2 802 b transmits a handover notify signaling to the MM807 (S807) and transmits a path switch request to the SM 808 (S808).

The SM 808 may determine whether to perform a UP NF relocation triggeredby the path switch request (S809). In this embodiment, the case of norelocation of the UP NF will be described. In case where the relocationof the UP NF is required, the SM 808 can proceed with additionalprocedures.

In addition, the SM 808 may transmit a session modification request tothe UP NF1 803 a (S810), and may receive a session modification responsefrom the UP NF1 803 a (S811).

Thereafter, when a path switch response is transmitted (S812) to theRAN2 802 b by the SM 808, the UE 801 may perform transmission/receptionof UL/DL traffic with the RAN2 802 b, the UP NF1 803 a, and the DN 804.In addition, the SM 808 may transmit a release resource signaling to theRAN1 802 a (S813), and a tracking area update procedure may be performedbetween the UE 801, the RAN1 802 a, the RAN2 802 b, and the MM 807(S814).

FIG. 9 is a diagram illustrating a tracking area update (TAU) procedurefor updating a location of a terminal (UE) in a network (e.g., MM)according to an embodiment of the present invention.

First, the UE 901 may transmit a TAU request to the MM 907 (S901). Inaddition, the UE 901 may perform an authentication and securityprocedure between the MM 907 and the SDM 905.

If the UE location is changed at the RAN level (or cell level), the MM907 sends a state change notify message to all SMs 908 associated withthe UE 901 (S903). At this time, the state change notify message mayinclude RAN ID update information.

The SM 908 that receives this message determines whether to perform UPNF relocation (S904). If the UP NF relocation is required, for example,if the relocation from the UP NF1 903 a to the UP NF2 903 b is required,this is written in a state change notify ack message and sent to the MM907 (S905). Upon reception of the state change notify ack message, theMM 907 transmits a TAU accept message to the UE 901 (S906). Here, theTAU accept message sent to the UE 901 may include (piggyback) the UP NFrelocation required information and the UN NF relocation information.

Thereafter, a session establishment procedure is performed between theUE 901, the RAN 902, the MM 907, the SM 908, the UP NF1 903 a, the UPNF2 903 b, the DN 904, and the SDM 905 (S907), and the SM 908 performs aPDU session release request/response process with the UP NF1 903 aS908).

FIG. 10 shows a process of deleting a data transmission path by a basestation (RAN) when the data transmission is not performed for a specifictime (for example, in case of user traffic inactivity) through a userplane (UP) transmission path of a PDU session already set up for aspecific terminal (UE). As described in FIG. 1, the NG3 interface isresponsible for the transmission path between the RAN and the UP NF, sothis procedure will be referred to as NG3 release. However, the name ofthe procedure may be changed.

Referring to FIG. 10, the RAN 1002 accessed by the UE 1001 may transmitan NG3 release request to the SM 1008 (S1001). For example, the RAN 1002operates a data inactivity timer for each PDU session, and if there isno traffic until the timer expires, may transmit, to the MM 1007, theNG3 release request signaling including identification information for aPDU session in which no traffic occurs. The MM 1007 that receives thesignaling confirms the PDU session identification information andforwards the request signaling to the SM 1008 that manages thecorresponding PDU session.

In response to this, the SM 1008 sends a signaling for releasing thetransmission path set for the UP NF 1003 and the RAN 1002. Specifically,the SM 1008 may transmit a N3 tunnel release signaling (e.g., releasesession request signaling) to the UP NF 1003 responsible for datatransmission of the PDU session (S1002). Upon receiving the signaling,the UP NF 1003 may transmit a release session response signaling to theSM 1008 (S1003).

Thereafter, the SM 1008 may transmit, to the RAN 1002, a signalingincluding an NG3 release command allocated for the N3 tunnel of thecorresponding PDU session (S1004). Then, the RAN 1002 may perform asignaling exchange such as RRC connection reconfiguration with the UE1001 to release the DRB corresponding to the session. For example, theRAN 1002 may send a radio bearer release signaling to the UE 1001(S1005).

In case of succeeding in releasing resources for all UP connections forthe corresponding PDU session, the RAN 1002 may transmit a responsesignaling to the SM 1008 via the MM 1007. For example, the RAN 1002 maysend an NG3 release complete signaling to the SM 1008 via the MM 1007.

If all the NG3 set for the UE 1001 is released, the UE 1001 furtherproceeds with an NG2 release with the MM 1007 (S1007) to release a nonaccess stratum (NAS) connection and thereby completely enter an idlestate.

FIG. 11 is a diagram illustrating a procedure for releasing a signalingconnection between a terminal (UE) and an MM according to an embodimentof the present invention.

The RAN 1102 may transmit an NG2 release request to the MM 1107 (S1101).If there is a non-released NG3 when this procedure is performed, the RAN1102 inserts the SM ID responsible for the non-released NG3 into the NG2release request. For example, the RAN 1102 may further insert PDUsession identification information (e.g., PDU session ID) in the requestand send it to the MM 1107.

In response to the above signaling, the MM 1107 may transmit an NG3release request signaling to the SM 1108 (S1102). If one SM 1108 managesa plurality of PDU sessions for one UE, the MM 1107 can correctlyidentify such PDU sessions, based on the PDU session identificationinformation. Then, the MM 1107 may send an NG3 release request to theidentified SM 1108.

The SM 1108 that receives the NG3 release request transmits a releasesession request to the UP NF 1103 (S1103), and receives a releasesession response from the UP NF 1103 (S1104).

Then, the MM 1107 that receives the NG 3 release response from the SM1108 sends an NG2 release command message to the RAN 1102 (S1106). Atthis time, the NG2 release command message may include an NG3 releasecommand to release NG3 resources of the RAN 1102.

The RAN 1102 that receives the NG2 release command transmits an RRCconnection release signaling to the UE 1101 (S1107), and also transmitsan NG2 release complete signaling to the MM 1107 (S1108).

FIG. 12 shows information necessary for the above-described procedurefor each entity. Each of the UE 1201 and the RAN 1202 separately managesthe MM ID and the SM ID, thereby distinctively transmitting a signalingassociated with the MM 1207 and a signaling associated with the SM 1208.

Through the above-described procedure, the UE 1201 and the RAN 1202 maymanage state information on the PDU session for each SM 1208. That is,it is possible to manage NG3 distinctively in case of being set up andin case of being released.

FIG. 13 is a block diagram illustrating a configuration of a terminal(UE) according to an embodiment of the present invention. Referring toFIG. 13, the UE 1300 according to an embodiment of the invention mayinclude a UE controller 1302 and a UE transceiver 1304. Also, the UEtransceiver 1304 may include a UE receiver 1304 a and a UE transmitter1304 b.

The UE transceiver 1304 according to an embodiment of the invention mayperform all the functions related to the transmission/receptionoperation of the UE in embodiments described with reference to FIGS. 1to 12. For example, the UE transceiver 1304 may transmit or receive aradio signal to or from a base station (RAN). The radio signal mayinclude control information and data. For example, when a radio beareris formed according to an embodiment of the invention, data may betransmitted to the base station through the radio bearer.

Although not shown in the drawings, the UE transmitter 1304 b mayinclude an RF transmitter for up-converting and amplifying a transmittedsignal, and the UE receiver 1304 a may include an RF receiver forlow-noise-amplifying and down-converting a received signal. In addition,the UE transceiver 1304 may receive a signal through a radio channel andoutput the signal to the UE controller 1302, and also transmit a signaloutputted from the UE controller 1302 through a radio channel.

In addition, the UE controller 1302 may control a series of processes sothat the UE can operate according to the above-described embodiments ofthe invention. For example, the UE controller 1302 may select a ProtocolData Unit (PDU) session for transmission of data from among at least oneinactivated PDU session, and control the transceiver 1304 to transmit aservice request message including identification information of theselected session to a mobility management function element for managingmobility of the UE. Also, the UE controller 1302 may control thetransceiver 1304 to transmit the data through the selected PDU sessionactivated based on the service request message.

FIG. 14 is a block diagram illustrating a configuration of a mobilitymanagement function (MMF) element according to an embodiment of thepresent invention. Referring to FIG. 14, the MMF 1400 according to anembodiment of the invention may include an MMF controller 1402 and anMMF transceiver 1404. Also, the MMF transceiver 1404 may include an MMFreceiver 1404 a and an MMF transmitter 1404 b.

The MMF transceiver 1404 according to an embodiment of the invention mayperform all the functions related to the transmission/receptionoperation of the MMF element in embodiments described with reference toFIGS. 1 to 12. For example, the MMF transceiver 1404 may receive, fromthe UE, a service request message including identification informationof a specific PDU session. Also, the MMF transceiver 1404 may transmit,to a specific session management function element corresponding to theidentification information of the specific PDU, a path setup triggermessage for data transmission to a user plane network function elementof the UE.

In addition, the MMF controller 1402 may control a series of processesso that the MMF can operate according to the above-described embodimentsof the invention. For example, when a signaling related to path setupfrom a specific session management function element, the MMF controller1402 may control the transceiver 1404 to forward the signaling to thebase station (RAN).

FIG. 15 is a block diagram illustrating a configuration of a sessionmanagement function (SMF) element according to an embodiment of thepresent invention. Referring to FIG. 15, the SMF 1500 according to anembodiment of the invention may include an SMF controller 1502 and anSMF transceiver 1504. Also, the SMF transceiver 1504 may include an SMFreceiver 1504 a and an SMF transmitter 1504 b.

The SMF transceiver 1504 according to an embodiment of the invention mayperform all the functions related to the transmission/receptionoperation of the SMF element in embodiments described with reference toFIGS. 1 to 12. For example, the SMF transceiver 1504 may receive, from amobility management function element for managing mobility of UE, a pathsetup trigger message for data transmission to a user plane networkfunction element of the UE. Also, the SMF transceiver 1504 may transmitsignaling related to the path setup to the mobility management functionelement.

In addition, the SMF controller 1502 may control a series of processesso that the SMF can operate according to the above-described embodimentsof the invention. For example, when a signaling related to path setupfrom a mobility management function (MMF) element, the SMF controller1502 may control the transceiver 1504 to transmit the signaling to theMMF.

Embodiments disclosed in the present specification and drawings are onlyillustrative of specific examples in order to facilitate description andunderstanding of the technical contents, and are not intended to limitthe scope of the present invention. It is to be understood by thoseskilled in the art that other modifications based on the technical ideaof the present invention are possible in addition to the embodimentsdisclosed herein.

While this disclosure contains many specific implementation details,these should not be construed as limitations on the scope of theinvention or of what may be claimed, but rather as descriptions offeatures that may be specific to particular embodiments of particularinvention.

1. A method performed by an access and mobility management function(AMF) in a wireless communication system, the method comprising:receiving, from a terminal in an idle state via a base station, aservice request message including information for identifying a protocoldata unit (PDU) session whose an user plane (UP) connection is to beactivated, the UP connection for forwarding data being configuredbetween the terminal and an user plane function (UPF); transmitting, toa session management function (SMF) associated with the PDU session, afirst message to activate the PDU session; receiving, from the SMF, asecond message including the information for identifying the PDU sessionand information on the UPF associated with the PDU session, as aresponse to the first message; and transmitting, to the base station, athird message including the information for identifying the PDU sessionand the information on the UPF associated with the PDU session.
 2. Themethod of claim 1, wherein the information for identifying the PDUsession includes a PDU session identifier (ID), and wherein theinformation on the UPF includes tunnel information of the UPF.
 3. Themethod of claim 1, further comprising: receiving, from the base station,a fourth message in response to the third message including tunnelinformation of the base station; and transmitting, to the SMF, a fifthmessage including the tunnel information of the base station, whereindownlink data is transmitted from the UPF to the terminal, after thefifth message is transmitted.
 4. The method of claim 1, wherein a dataradio bearer between the terminal and the base station is setup based onquality of service (QoS) information of the PDU session.
 5. The methodof claim 1, wherein only the UP connection of the PDU session isactivated for uplink data among UP connections of a plurality of PDUsessions established for the terminal.
 6. A method performed by aterminal in a wireless communication system, the method comprising:identifying uplink data to be transmitted in an idle state;transmitting, to an access and mobility management function (AMF) via abase station, a service request message including information foridentifying a protocol data unit (PDU) session whose an user plane (UP)connection is to be activated, the UP connection for forwarding databeing configured between the terminal and an user plane function (UPF),wherein a message to activate the PDU session is transmitted from theAMF to a session management function (SMF) associated with the PDUsession, and wherein the information for identifying the PDU session andinformation on the UPF associated with the PDU session is transmittedfrom the SMF to the base station via the AMF; receiving, from the basestation, a radio resource control (RRC) message for setting up a dataradio bearer for the PDU session; and forwarding, to the UPF, the uplinkdata via the data radio bearer.
 7. The method of claim 6, wherein theinformation for identifying the PDU session includes a PDU sessionidentifier (ID), and wherein the information on the UPF includes tunnelinformation of the UPF.
 8. The method of claim 6, wherein downlink datais received from the UPF, after tunnel information of the base stationis transmitted from the base station to the SMF via the AMF.
 9. Themethod of claim 6, wherein the data radio bearer between the terminaland the base station is setup based on quality of service (QoS)information of the PDU session.
 10. The method of claim 6, wherein onlythe UP connection of the PDU session is activated for the uplink dataamong UP connections of a plurality of PDU sessions established for theterminal.
 11. An access and mobility management function (AMF) in awireless communication system, the AMF comprising: a transceiver; and acontroller configured to: control the transceiver to receive, from aterminal in an idle state via a base station, a service request messageincluding information for identifying a protocol data unit (PDU) sessionwhose an user plane (UP) connection is to be activated, the UPconnection for forwarding data being configured between the terminal andan user plane function (UPF), control the transceiver to transmit, to asession management function (SMF) associated with the PDU session, afirst message to activate the PDU session, control the transceiver toreceive, from the SMF, a second message including the information foridentifying the PDU session and information on the UPF associated withthe PDU session, as a response to the first message, and control thetransceiver to transmit, to the base station, a third message includingthe information for identifying the PDU session and the information onthe UPF associated with the PDU session.
 12. The AMF of claim 11,wherein the information for identifying the PDU session includes a PDUsession identifier (ID), and wherein the information on the UPF includestunnel information of the UPF.
 13. The AMF of claim 11, wherein thecontroller is further configured to control the transceiver to receive,from the base station, a fourth message in response to the third messageincluding tunnel information of the base station, and control thetransceiver to transmit, to the SMF, a fifth message including thetunnel information of the base station, and wherein downlink data istransmitted from the UPF to the terminal, after the fifth message istransmitted.
 14. The AMF of claim 11, wherein a data radio bearerbetween the terminal and the base station is setup based on quality ofservice (QoS) information of the PDU session.
 15. The AMF of claim 11,wherein only the UP connection of the PDU session is activated foruplink data among UP connections of a plurality of PDU sessionsestablished for the terminal.
 16. A terminal in a wireless communicationsystem, the terminal comprising: a transceiver; and a controllerconfigured to: identify uplink data to be transmitted in an idle state,control the transceiver to transmit, to an access and mobilitymanagement function (AMF) via a base station, a service request messageincluding information for identifying a protocol data unit (PDU) sessionwhose an user plane (UP) connection is to be activated, the UPconnection for forwarding data being configured between the terminal andan user plane function (UPF), wherein a message to activate the PDUsession is transmitted from the AMF to a session management function(SMF) associated with the PDU session, and wherein the information foridentifying the PDU session and information on the UPF associated withthe PDU session is transmitted from the SMF to the base station via theAMF, control the transceiver to receive, from the base station, a radioresource control (RRC) message for setting up a data radio bearer forthe PDU session, and control the transceiver to forward, to the UPF, theuplink data via the data radio bearer.
 17. The terminal of claim 16,wherein the information for identifying the PDU session includes a PDUsession identifier (ID), and wherein the information on the UPF includestunnel information of the UPF.
 18. The terminal of claim 16, whereindownlink data is received from the UPF, after tunnel information of thebase station is transmitted from the base station to the SMF via theAMF.
 19. The terminal of claim 16, wherein the data radio bearer betweenthe terminal and the base station is setup based on quality of service(QoS) information of the PDU session.
 20. The terminal of claim 16,wherein only the UP connection of the PDU session is activated for theuplink data among UP connections of a plurality of PDU sessionsestablished for the terminal.